The present invention relates to optical bar code scanning systems and more particularly to a portable bar code scanner which doesn't require a hand operated trigger to initiate an operation of the bar code scanner.
In present-day merchandising point-of-sale operations, data pertaining to the purchase of a merchandise item is obtained by reading data encoded indicia such as a bar code label printed on or attached to the merchandise item. In order to standardize the bar codes used in various point-of-sales check out systems, the grocery industry has adopted an uniform product code (UPC) which is in the form of a bar code. Reading systems which have been constructed to read this type of bar code include hand-held wands which are moved across the bar code, and stationary optical scanning systems normally located within the cabinet structure of a checkout counter, in which the bar code is read when a purchased merchandise item is moved across a window in a counter constituting the scanning area of the counter. Other reading systems employ hand-held laser scanners which emit a single or multiple line scan pattern which are manually moved past the bar code label that is to be read. These prior bar code hand-held scanners employ a trigger mechanism which has to be actuated to initiate the operation of the scanner. It has been found that the use of such a trigger mechanism has led to hand fatigue in the operator increasing the occurrence of reading failures in the scanning operation.